it is your body and your birth and entierly your decision.
I am sure your family is upset that they wont be there to 'support' you, but My guess is they are more disapointed that they wont be there for the magical first moments of your bub entering the world.
You as the birthing mother, and your DP as the father, have final say over what is and isnt right for YOU (and the baby)
I had a birth plan very similar to yours (a few days to bond as a family first) I felt this was SO important especial as it was our 1st (and 2nd) Its such a life changing event, and important that you get a grip on it before concerning anyone else.
I will not lie to you, I had alot of critism to deal with after sticking firm with my decision.
I do not regret the decision I made, but I do still hold a grude against certin family members who has the nerve to make me 'pay' for excluding them from the birth (months and months of cold shoulder and passive aggressive comments)
At the time, it was the best decision for me and my babys.
This topic still makes me mad. I do not understand why other people think they have the RIGHT to be present. I am sure they love the mother, father and unborn child very much, but love MUST extend to a trust that the mother and father know what is best for them and their new family. there is not much difference between a hour old baby and a 3 day old baby anyway.